In this paper, the basic elements related to the selection of participants for a health research are discussed. Sample representativeness, sample frame, types of sampling, as well as the impact that non-respondents may have on results of a study are described. The whole discussion is supported by practical examples to facilitate the reader's understanding.
To introduce readers to issues related to sampling.
Dermatology; Epidemiology and biostatistics; Epidemiologic studies; Sample size; Sampling studies